Search results
Results from the WOW.Com Content Network
The sender also adds a counter (emitter timeout). If the counter ends without receiving confirmation, the sender assumes packet loss, and sends the frame again. Piggybacking introduces a complication not present with separate acknowledgements. How long should the data link layer wait for a packet onto which to piggyback the acknowledgement?
Request–response pattern can be implemented synchronously ( such as web service calls over HTTP) or asynchronously. [1] In contrast, one-way computer communication, which is like the push-to-talk or "barge in" feature found on some phones and two-way radios, sends a message without waiting for a response.
Alice replies with an acknowledgment (ACK) message with acknowledgement number +, which Bob receives and to which he doesn't need to reply. In this setup, the synchronize messages act as service requests from one server to the other, while the acknowledgement messages return to the requesting server to let it know the message was received.
The acknowledgement function is used in the automatic repeat request (ARQ) function. Acknowledgement frames are numbered in coordination with the frames that have been received and then sent to the transmitter. This allows the transmitter to avoid overflow or underrun at the receiver, and to become aware of any missed frames.
The initiating host A sends an RRQ (read request) or WRQ (write request) packet to host S at port number 69, containing the filename, transfer mode, and optionally any negotiated option under the terms of RFC 2347. S replies with an option ACK if options were used, and an ACK (acknowledgment) packet to WRQ and directly with a DATA packet to RRQ.
A non-standard but widely used way to request return receipts is with the "Return-Receipt-To:" (RRT) field in the e-mail header, with the email return address specified. The first time a user opens an email message containing this field in the header, the client will typically prompt the user whether to send a return receipt.
If you've just passed an image challenge, but are immediately prompted by another, there may be an issue with your browser. Before you attempt another image challenge, clear the cache on your web browser. If you're still prompted to retake the image challenge multiple times a day, you might have a more serious issue.
Retransmission, essentially identical with automatic repeat request (ARQ), is the resending of packets which have been either damaged or lost. Retransmission is one of the basic mechanisms used by protocols operating over a packet switched computer network to provide reliable communication (such as that provided by a reliable byte stream, for example TCP).